non-resident state tax

In response to your first question, it depends.  In September 2021, MA ended the temporary regulations the state had put in place regarding teleworkers.  Now, the rules in effect in MA are as follows:

Nonresidents. All compensation received for services performed by a nonresident who, immediately prior to the Massachusetts COVID-19 state of emergency was an employee engaged in performing such services in Massachusetts, and who is performing services from a location outside Massachusetts due to a pandemic-related circumstance, will continue to be treated as Massachusetts source income subject to personal income tax under M.G.L. c. 62, § 5A and personal income tax withholding pursuant to M.G.L. c. 62B, § 2. (See 830 CMR 62.5A.3(3)(a).)

A nonresident employee who, prior to the Massachusetts COVID-19 state of emergency, determined Massachusetts source income by apportioning based on days spent working in Massachusetts in accordance with 830 CMR 62.5A.1(5)(a), must continue to do so based on: (1) the percentage of the employee's working days spent in Massachusetts during the period January 1 through February 29, 2020 as determined under 830 CMR 62.5A.l(5)(a); or (2) if the employee worked for the same employer in 2019, the apportionment percentage properly used to determine the portion of employee wages constituting Massachusetts-source income on the employee's 2019 return. (See 830 CMR 62.5A.3(3)(b).)

So, in response to your first question, the answer will depend at least in part as to why you began working from home.  Was it COVID-19 related?  If so, it would appear that your wages are subject to tax by MA.  If not, then the paragraph above that relates to allocating time spent appears to apply. 

No, as to your second question.  Unreimbursed employee expenses are no longer deductible on a tax return.